Display panels of the dot matrix type wherein light emitting cells such as LEDs are arranged at fixed distances in rows and columns have spread popularly and widely. On a simple LED display panel which is used for a guide display in an electric car or an advertisement display of a store, principally a character train is scrolling displayed on a display panel of a limited size. For example, character train data of the bit map type wherein one character is composed of 16.times.16 dots are successively produced and displayed by scrolling on a display panel of the dot matrix type wherein sixteen (16) dots are arranged in a column and a number of dots greater than at least several times as large as sixteen (16) are arranged in a row.
For example, where a character train is displayed by feeding (displayed by scrolling) in a horizontal direction on such a horizontally elongated display panel of the dot matrix type as described above, in order to increase the number of characters which can be displayed at a time, naturally the number of dots in the horizontal direction of the display panel must be increased. Accordingly, a considerable increase in cost is required for such simple expansion of a display panel.
Meanwhile, if the distances between light emitting cells arranged in rows and columns are increased to increase the size of a display panel in order to provide a display of a large size, a display image becomes very rough and the display quality is deteriorated remarkably. Therefore, the size of a display panel is increased by increasing the number of light emitting cells without increasing the distances between the light emitting cells very much. Meanwhile, the definition of display data is increased by constructing one character with 32.times.32 dots or the like. By such countermeasures, a display of a large size and a high quality can be obtained. However, a remarkable increase in cost must be expected for the countermeasures.
Further, in a conventional display panel of the dot matrix type, irrespective of whether the size thereof is large or small, a large number of light emitting cells are mounted on a circuit board and accommodated in a flat panel type case together with a drive circuit. Naturally, the display panel has a rigid body and is not so flexible as to allow it to be folded freely (although it may be divided into several parts), divided into small parts or contracted or expanded. While a display panel of a very small size can be carried entirely (some display panels for advertisement of a store are portable), most of display panels of the type described are installed fixedly at predetermined locations. This apparatus form is considered to be one of obstacles to expansion in application.